Sculptor Galaxy
The Sculptor Galaxy, also known as the Silver Coin or Silver Dollar Galaxy, NGC 253, is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation. The Sculptor Galaxy is located at the center of the Sculptor Group, one of the nearest groups of galaxies to the Milky Way.The Sculptor Galaxy (the brightest galaxy in the group and one of the intrinsecally brightest galaxies in the vicinity of ours, only surpassed by the Andromeda Galaxy and the Sombrero Galaxy ) and the companion galaxies NGC 247, PGC 2881, PGC 2933, Sculptor-dE1, and UGCA 15 form a gravitationally bound core near the center of the group. Most other galaxies associated with the Sculptor Group are only weakly gravitationally bound to this core. Starburst NGC 253's most notable feature is the mentioned starburst that is taking place of it and that has created several super star clusters on NGC 253's center discovered with the aid of the Hubble Space Telescope: one with a mass of 1,5*106 solar masses, and absolute magnitude of at least -15 and two others with 5*104 solar masses and absolute magnitudes around -11; later studies have discovered an even more massive cluster heavily obscured by NGC 253's interstellar dust with a mass of 1,4*107 solar masses, an age of around 5,7*106 years, and rich in Wolf-Rayet stars. Star formation is also high in the northeast of NGC 253's disk, where a number of red supergiant stars can be found, and on its halo are present young stars as well as some amounts of neutral hydrogen. This, along other peculiarities found on NGC 253, suggest a gas-rich dwarf galaxy collided with it 200 million years ago, disturbing its disk and starting the present starburst. Although supernovae are generally associated with starburst galaxies, only one supernova has been detected within the Sculptor Galaxy. The supernova, named SN 1940E, is located approximately 54″ southwest of the galaxy's nucleus. It was discovered in November 1940. Recent distance estimateseditAt least two techniques have been used to measure distances to Sculptor in the past ten years. Using the planetary nebula luminosity function method, an estimate of 10.89 +0.85 −1.24 Mly (3.34 +0.26 −0.38 Mpc) was achieved in 2006. Sculptor is close enough that the tip of the red giant branch (TRGB) method may also be used to estimate its distance. The estimated distance to Sculptor using this technique in 2004 yielded 12.8 ± 1.2 Mly (3.94 ± 0.37 Mpc). A weighted average of the most reliable distance estimates gives a distance of 11.4 ± 0.7 Mly (3.5 ± 0.2 Mpc). Sculptor is the target of a large Union Expedition reaching its destination in 5060 Constellation Sculptor *Right ascension 00h 47m 33s1 *Declination -25° 17′ 18″1 *Redshift 0.0008111 *Helio radial velocity 243 ± 2 km/s 1 *Distance 11.4 ± 0.7 Mly * (3.5 ± 0.2 Mpc)2 *Type SAB(s)c1 *Apparent dimensions (V) 27′.5 × 6′.81 *Apparent magnitude (V) 8.01 *Other designations *Silver Coin Galaxy,1 Silver Dollar Galaxy,3 NGC 253,1 UGCA 13,1 PGC 27891 Caldwell 65 *See also: Galaxy, List of galaxies Category:Space